Resistive random-access memory (RRAM) has the potential to become the front runner among other non-volatile memories because of the benefits of the high-capacity, the fast switching speeds, the endurance of 1 billion write/read cycles, the lower currents and voltages, and the simpler and smaller cell structure.
Conductive-bridging random access memory (CBRAM) is one of the noticed non-volatile memories. The basic memory cell of CBRAM is composed of a solid electrolyte, e.g. Ag—Ge—Se and Cu/WO3, sandwiched between two metal layers to form a programmable structure. Through the presence or absence of a metal channel formed in the solid electrolyte resulted from the reduction or the oxidation reactions of the metal ions in the solid electrolyte, the programmable structure can be used to store non-volatile information.
Please refer to FIG. 1, which is a diagram showing a conductive-bridging random access memory according to the prior art. In FIG. 1, the top electrode is an oxidizable electrode 10 where the oxidation and the reduction reactions will take place when a sufficient working voltage is applied thereto, and the bottom electrode is an inert electrode 11. For example, the material Ag could be used to form the oxidizable electrode 10 while the electrolyte is Ag—Ge—Se. When a sufficient negative voltage is supplied to the inert electrode 11, electrons will flow into the solid electrolyte 12 from the inert electrode 11 for initiating a reduction reaction of the metal ions in the solid electrolyte 12, and meanwhile, the reduced metal ions in the solid electrolyte 12 could be supplemented by the metal ions derived from the oxidation reaction at the oxidizable electrode 10. If the negative voltage is applied for a sufficient length of time, the metal atoms forms a plurality of dendrite structures 13 and grows from the inert electrode 11 toward the oxidizable electrode 10 by the continuous reduction reactions until any one of the dendrite structures 13 reaches the oxidizable electrode 10. The dendrite structure 13 connecting the oxidizable electrode 10 and the inert electrode 11 is a metal channel where the current passes through. During the formation of the metal channel, too many and too large dendrite structures 13 formed in the solid electrolyte 12 all cause the consumptions of voltage and metal materials. Furthermore, the differential growth rates of the metal channels between different memory cells cause the significant differences in the wording voltages and currents between different memory cells.
Hence, because of the defects in the prior arts, the inventors provide a non-volatile memory cell and fabrication method thereof to effectively overcome the demerits existing in the prior arts.